I have a love/hate relationship with Games Workshop. I could go on for hours about the hate side of it, but I think everyone is aware of the normal criticisms of GW by now. I do love the Warhammer universe though, and from time to time they put out some really cool games. It seems that their best games aren't always the most popular though, and they aren't given the long term support that they deserve. Necromunda, Epic 40k, GorkaMorka. Adeptus Titanicus all fall into this category, as does Mordheim.
If you aren't familiar with it, Mordheim is a skirmish level fantasy combat game, fitting somewhere in between an RPG and wargame. Each player has a warband of about 5-20 models. The game centers on the city of Mordheim which has been destroyed by a comet, and the bands of adventures that have come to plunder the remains of the city and gather the precious magical warpstone from the comet. The warbands are themed units based on different troop types from around the Empire, and some more more monstrous units like beastmen and skaven. Over the course of time, official and unofficial warband lists have been created for just about every sort of Warhammer army and troop type.
What I love about the game is that it doesn't require a lot of work or time, yet is very fun and has a lot of replay value. Collecting an army of over 100 miniatures is a daunting task, not to mention expensive. 15-20 is great for a beginner or those that are short on cash, space and/or time. There are also plenty of ideas for scenarios, and the campaign rules give the game depth and purpose. The rules are fairly simple, being a slightly modified version of Warhammer Fantasy Battles, the major difference being that units don't "form up" in blocks, thus removing the need for a lot of the movement rules.
In short, Mordheim is everything Battlesystem Skirmishes could have been. With a focused and detailed setting, thematic army lists and campaign rules, Mordheim is a complete game, not just a set of rules. Yet, if you wanted to, you could take he skeleton of those rules, and use it for a different purpose, say an RPG?
GW lists this as a Specialist game, which mean they aren't producing new material for it, and most of the rules and miniatures have to be ordered online. It also means they aren't running games in the stores, which is a shame because I think it is a great way to introduce people to the hobby. Fortunately there is still some good fan support for the game, and a revised set of rules named "Coreheim" is freely available.